.img {
    width: 320px;
    height: 180px;
    background: url('./img/降魔大圣\(缩小版\).jpg');
    background-size: contain;
    position: relative;
}

.img .mask {
    width: 50px;
    height: 50px;
    background: yellow;
    opacity: .5;
    position: absolute;
    left: 0px;
    top: 0px;
    display: none;
}

.enlarge {
    width: 100px;
    height: 100px;
    background-color: rebeccapurple;
    background: url('./img/降魔大圣\(缩小版\).jpg');
    background-position: 0px 0px;
    display: none;
}